DERIVATIVES AND HEDGING ACTIVITY - Undesignated Interest Rate Derivatives (UNITED DOMINION REALTY, L.P.) (Details) $ in Thousands	Jun. 30, 2020 USD ($)
United Dominion Realty L.P. \| Interest rate contracts \| Other assets \| Not Designated as Hedging Instrument
Fair value of Company's derivative financial instruments and their classification on Consolidated Balance Sheet
Derivative Asset Not Designated as Hedging Instrument, Fair Value	$ 8

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant